The present invention concerns a process for storing heat with compositions containing at least one saturated aliphatic hydrocarbon.
The problem posed in storing heat from a source which furnishes heat energy only in an intermediate manner has been the object of numerous studies. This is particularly true for storing heat of solar origin, which it is desirable to be able to use in periods other than during sunshine, for example at night.
Among the materials which can be used as reserves for heat, there have been proposed materials which store heat without changing physical state, notably water. In this case, it is the specific heat which is utilized.
It has also been proposed to use materials which change state during storage; these are materials with a high latent heat of fusion, such as hydrates of salts, e.g. the hydrate of sodium sulphate Na.sub.2 SO.sub.4. 10 H.sub.2 O, or paraffinic hydrocarbons which are solid at ambient temperature. In this case it can further be a question of a well defined paraffinic hydrocarbon or a mixture of hydrocarbons.
The use of such paraffinic hydrocarbons however makes it necessary that they have particular properties, notably;
a sufficiently low melting point;
a well defined melting point, in the case of mixtures, because the difference in density between the solid phase and the liquid phase creates a separation which reduces the usable latent heat;
a high chemical inertness to avoid corrosion of equipment.
These particular properties are not always possessed by the available paraffinic hydrocarbons and notably mixtures of hydrocarbons derived from the refining of crude petroleum.
The work carried out by the Applicant has enabled him to conceive of a means for facilitating the use of saturated aliphatic hydrocarbons for the storing of heat. The object of the present invention is therefore the storing of heat with saturated aliphatic hydrocarbons.